KYBBY ID Tips: Jewelweed Seedlings

(Cross-posted from the KNPS Wildflower Week BotanyBlitz journal)

In March and early April, along wet roadside ditches, moist woodland openings, and shaded floodplains, you may find an abundance of a certain conspicuous seedling having large, rounded leaves that are shallowly notched at the tip:

(seedling pics by @terrikoontz)

These rubbery, bluish-green, and decidedly chonky cotyledons belong to Kentucky's two native Jewelweed species, the orange-flowered Impatiens capensis and the yellow-flowered Impatiens pallida. Both species have seed leaves that are distinctively oversized, with each leaf about the size of a quarter. As the stem begins to elongate, these seed leaves give way to the plant's true leaves, which are hairless, ovate, and broadly toothed along the edges:

(Jewelweed plants with stem leaves and cotyledons still attached by @mewells)

I'm not aware of a reliable way to identify Jewelweed seedlings to species, although later in the spring when the plants are larger, you can tell them apart before flowering time by examining the teeth along the leaf edges: the leaves of Impatiens capensis generally have 9 or fewer teeth on each side of the leaf, while those of Impatiens pallida usually have 10+ teeth per side.

A caveat!

There may be a few species with seedlings that are somewhat similar, but Jewelweed is unique in having the largest and broadest seed leaves you're likely to encounter in its preferred habitats.

Waterleaf (Hydrophyllum) species also have fairly prominent seed leaves (more or less the size of a nickel), but they're still mostly smaller than Jewelweed and are softly hairy, whereas Jewelweed is hairless, rubbery, and blue-green all over. Here's what Great Waterleaf looks like as a wee baby, if you zoom in you can see the soft fuzz on its leaves:

https://www.inaturalist.org/observations/72217256
https://www.inaturalist.org/observations/71846387

Posted on March 29, 2022 11:24 AM by vvoelker